I have purchased 4 ft. by 8 ft. high quality pine benchwork which will be in a room on the first floor of my house. I will use 2 inch foam board on top of the benchwork.
I live in N. VA where the humidy in the room can vary from 35% to 60% and some times at a peak of 80% since I do not run the AC continuously.
Do I need to seal the wood so it does not warp, or not?
thanks,
Bob in McLean VA
I recommend YES, a simple paint job should do the trick. It doesn't take much expansion and contraction to to warp your track. Even though you'll seal it, there's always a chance it could still shrink/swell, try to leave some gaps in the rail when laying your track. The gap could be be about the thickness of a credit card and every other joint should be ok.
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I haven't ever painted or sealed my model railroad benchwork and have not had any problems. My last two layouts in VA were a lot larger than your 4x8 and had no problems. You do have to plan for some expansion and contraction issues with ANY model roairoad, but with a 4x8, they will not be much.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
My layout is in a room with heat and AC. I have open-grid benchwork, no plywood, with a pink foam base. My wife insisted that the wood be stained or painted. I sanded it to get a good surface, stained it and covered it with 2 coats of polyurethane. It's not "furniture," but it looks pretty good and certainly helps to "promote domestic tranquility."
And, it's a lot easier to do now rather than wait until you've got trains on it.
It takes an iron man to play with a toy iron horse.
Though the foam should not be affected by humidity, a good coat of sealer or paint on the wood is cheap insurance. Not nearly as easy to go back if there is a problem, than to do it in the first place.
Good luck,
Richard
Bob,
Yeah, you'll get a range of opinion on this one. On the first floor, I'd be inclined to skip it, unlike in the basement where it might be advisable. The comments about apperance are pertinent, as you're on the first floor and I'm sure your RR wants to be a good neighbor.
Mike Lehman
Urbana, IL
Haven't really had an trouble with humidity doing anything to my benchwork in Alexandria and I can see river out my window, so it's slightly more humid (back in the old days, they'd go all the way out to Falls Church to escape the heat and humidity of Washington and Alexandria!)
Paint wouldn't hurt, but I'm not sure I'd bother.
Although my layout is in a controlled environment, I painted all the benchwork and roadbed (Homabed) to be on the safe side. And although the wood was very attractive in its raw state (Siemens), the benchwork looks better finished.
Dante
If you do decide to seal it make sure you do the whole thing in one day. We recently painted the subroadbed plywood on a club members layout after about 3 years of it being in his basement. We didnt have the paint to finish it. When we came back the next week everywhere we had not painted the rails where kinked horribly.
Connecticut Valley Railroad A Branch of the New York, New Haven, and Hartford
"If you think you can do a thing or think you can't do a thing, you're right." -- Henry Ford
I'm in central TX, overall relatively dry but we're next to a river, so maybe aveerage. In the climate controlled house, I did not seal my 5/8" plywood subroadbed. Suggest in this area considering your spacing between supporting joists, as closer spacing would retuce the extent of warping between joists. If you do not seal everything, maybe consider sealing (after pre-cutting) any thin subroadbed strips for track rises that may tend to warp or twist more than large flat sections.
Paul
Modeling HO with a transition era UP bent
I have finished (painted) wooden benchwork in places where humidity might be a problem, on the theory that it's better to be safe than sorry.
My present layout has completely unpainted benchwork. I don't see any need to paint galvanized steel in a low (single digit) humidity environment.
Chuck (Modeling Central Japan in September, 1964 - on steel stud benchwork)
One place where sealing is often overlooked is the bottom of wood support members, where they contact a concrete or tiled surface. Water/ moisture can penetrate the wood fiber from that point and cause swelling or unevenness over time. When you paint, paint every surface, not just the visible ones.
Cedarwoodron
I also live in metro west DC area (work in Alexandria but commute from Manassas) so weather is the same. I'm building a layout in my basement and like you don't run the a/c all the time, only as necessary. I do have a dehumidifier in the basement to control humidity when necessary.
I have never heard of anyone sealing wood against humidity but it can't hurt. What I do seal is the homosote I use; being a pressed paper product, it would be much more prone to deformation due to moisture so I painted it on both sides and the edges to minimize issues.
By the way, I use homosote because I much prefer track nails and spikes (old school) vs. foam. If you lay track on foam, you have to use adhesive - and therefore have to be able to lay it "dead-on correct the first time. In my layout so far I've had to remove track multiple times to adjust it or do something I forgot, and then put it back. To me, the need to lay track correct first time is a major disadvantage of foam/adhesive track laying method. I do plan to use foam for scenery however, just not as a track subroadbed.
Cheers, Jim
Rio Grande. The Action Road - Focus 1977-1983
My layout is in a basement which gets damp and cold only in the change from winter to spring (when the house is warm enough that the furnace does not turn on, but the basement still is cool and damp feeling). I have not sealed the benchwork lumber per se but much of the wood was in my basement for at least a season before it was used for benchwork so it went through the full cycle -- and the top of the plywood was painted dark brown because I found it more motivating to lay track on a dirt toned top and found the broad expanse of unpainted plywood to be depressing.
I think having both the pine and the plywood inside my basement for a year was helpful - or at least was not a bad idea.
I use homasote and like Jim (above) sealed it. Following some old advice from Jim Hediger I used old fashioned shellac because it is liquid but has no water in it. Apart from the odor (which reminded me of a dozen cub scout projects) I had no problem with the shellac, but it does make the homasote less soft and probably decreases its sound deadening qualities a bit.
Dave Nelson
From my experience with wooden boats - which see a larger humidity swing than your house does - paint does not "seal" wood, nor does it prevent moisture from being absorbed or off-gassed from the wood. Paint does slow the passage of moisture into/out of the wood so that in an unstable humidity environment, the peaks of absorbtion/dryness will not be reached.
Wood fibers swell mostly in diameter depending on water content (up to 5% difference). There is some fiber enlongation with water content, but typically less than 1/4 as much as in diameter.
Painted wooden boats typically took 2-3 days to reach their final size when first put into the water, with 75% of the swelling taking place in the first 8 hours. This was with very high quality epoxy and urethane paint.
The only way to truly seal wood is to encase it with something like fiberglass. Sealing wood works well in boats until the seal is broken. Then the wood expands and/or rots (the latter because it can't breathe adequately).
Thick wood tends to warp more than thin because of the uneven moisture levels in the wood. Which is also why storing wood before using to let it uniformly adjust to the prevailing humidity is a good idea. Because plywood has many thin layers, it will have a more uniform moisture content, and will warp less. The multiple layers glued with crossed grain constrain the plywood from shrinking or expanding as anywhere near as much as lumber. Still, an 8ft length of plywood can grow/shrink 1/2" under extreme conditions.
Homasote, being wood pulp and glue based, has similar expansion/contraction as the supporting wood structure, and therefore needs no sealing beyond what the wood gets. I have seen Homasote siding on buildings in coastal Alaska, where humidity extremes are common. There was no self-destruction because the Homasote moved with the frame. I have personally had Homasote sheet edges sit in water puddles for a couple of days. They would swell, but would come back to size when dry. Discolored, but no deformation. Mind you, this is for true Homasote. For many years, there were/are "Homasote equivalents" being sold as Homasote that do not react to water/himidity as well as the real stuff - I know, I was sold Celotex as a suitable replacement for Homasote.
just my experiences
Fred W
NO PAINT - latex type paints don't seal. Only natural coatings such a varnish and shellac will seal the wood. We who are old enough to have owned wooden sailboats would never consider sealing the hull with glass fibre as the fibers are miniture straws that absord huge quantities of water and delaminate if it is fresh water. Only salt water seals these little fibre straws--varnish your boat--varnish your railroad.
Varnish can easily be dyed to any color hue.
Our benchwork is not a boat floating in water or even the exterior siding enclosing a home. Latex paints are used all the time to finish and protect the exterior siding of a home. Latex paint is an adequate protection for benchwork to mitigate the effect of humidity variation.
Paint does not mitigate humidity variation unless the variation is on a daily or shorter cycle. That was the point I was illustrating with wooden boats. You can leave your benchwork unpainted - which I do except for the fascia - and get exactly the same amount of expansion/contraction of the wood in normal household settings. The wood simply adjusts to the environmental moisture content a little faster if left unpainted.
The expansion/contraction of quality plywood is pretty negligible for normal humidity variations, which is why it is favored for modular construction.
If you are building during high humidity, leave no gaps in the track. If you are building during low humidity, leave 1/16 inch gap or so between flex track sections for expansion during high humidity.
If you solder track pieces on curve, and leave the 1/16" gaps on straights only, you will likely be OK if the humidity swings are not extreme. If you solder all rail joints, you better have the humidity pretty well controlled.
If you are putting foam inside a wood frame, the wood frame is still going to expand/contract with humidity changes. If the foam is semi-free floating on top of a wood support structure, then the track will not move as much with humidity - depending on roadbed material and other considerations.
If I wanted to seal Homasote, should I use varnish, or shellac?
(My last railroad started with foam with the track held down with caulk. Halfway through I switched to spiking track on Homasote. I'll never use foam for roadbed again.)
Also, I painted the Homasote, and it still swelled in high humidity even with a dehumidifier. Like others have said, latex paint does not create a seal. But it does make the Homasote more inviting for track laying.
Disclaimer: This post may contain humor, sarcasm, and/or flatulence.
Michael Mornard
Bringing the North Woods to South Dakota!
I am in the paint manufacturing biz. Have been all of my professional career. Sorry to disappoint everyone but the fact is consumer paints do not seal out moisture. All paints have a vapor transmission rating. None are zero. In fact, water vapor transmission is a desirable property in paint otherwise it will blister and/or delaminate. Paint must pass moisture in order to stay firmly attached to the substrate. After all, all surfaces have moisture present on them when they are painted as a result of there being humidity. Paint will slow down moisture transfer but in the end same same.
If you are dead set on painting benchwork then use a 2 component (ideally) or a single component moisture cure epoxy coating like used for garage floors. These coatings have the lowest vapor transmission rating of all consumer paint products with the exception of swimming pool paints but who wants aqua colored benchwork. Avoid latex paints. Waste of time to apply them if water vapor resistance is your goal.
As a previous poster noted, you have to paint every bit of the wood - top, bottom, sides, edges else your work will be in vain.
Alan
Freelancing the LK&O Railroad
Worked in the paint business all your career? How dare you actually know what you're talking about! This is the Internet!( )